ELEMENTARY STEPS OF THE INTERACTION OF C-H FILM SURFACES WITH THERMALH D ATOMS/

The interaction of thermal H and D atoms with thin ion-beam deposited C : H films were studied with vibrational (HREELS) and Auger electron spectroscopy. At surfaces which exhibit aromatic sp(2) CH groups a hyd rogenation reaction towards sp(3) is observed with a cross-section of 4.5 Angstrom(2). At fully hydrogenated C : H surfaces with solely sp(3 ) CH groups present, H abstraction towards molecular HD occurs at D im pact with an initial cross-section of 0.05 Angstrom(2). The magnitude of both cross-sections is in line with an Eley-Rideal mechanism. As a radical C atom is produced by the H abstraction reaction, a thermally activated de-excitation via a hydrocarbon radical split-off is initiat ed which causes chemical erosion of the C : H film at a yield of about 0.01 C per incoming H around 600 K.